No Trouble Found (NTF) is a term used primarily in the electronics industry referring to a system or component that has been returned to the manufacturer, supplier, or distributor due to some failure, but that fails to exhibit the failure to the original manufacturer. For example, a product may be returned for replacement or for service repair, but the product may operate properly when tested. This situation can also be referred to as No Defect Found (NDF). NTF returns can erode profit margins for manufacturers and service providers. The time, materials, and shipping costs in exchanging hardware are significant in relation to the cost of the item being replaced. Further, NTF returns can also indicate that customer problems have not been resolved: reducing customer satisfaction and eroding brand value. As a general proposition, effectively addressing these problematic testing issues presents a significant challenge to equipment vendors, electronics suppliers, and system designers alike.